H.I. Jang

Indications of neutrino oscillation in a 250 km long-baseline experiment.

The K2K experiment observes indications of neutrino oscillation: a reduction of nu(mu) flux together with a distortion of the energy spectrum. Fifty-six beam neutrino events are observed in Super-Kamiokande (SK), 250 km from the neutrino production point, with an expectation of 80.1(+6.2)(-5.4). Twenty-nine one ring mu-like events are used to reconstruct the neutrino energy spectrum, which is better matched to the expected spectrum with neutrino oscillation than without. The probability that the observed flux at SK is explained by statistical fluctuation without neutrino oscillation is less than 1%.

Near muon range detector for the K2K experiment: Construction and performance

A muon range detector (MRD) has been constructed as a near detector for the KEK-to-Kamioka long-baseline neutrino experiment (K2K). It monitors the neutrino beam properties at the near site by measuring the energy, angle and production point of muons produced by charged-current neutrino interaction. The detector has been working stably since the start of the K2K experiment.

Measurement of B(Ds+ → μ+νμ)B(Ds+ → φμ+νμ) and determination of the decay constant fDs

We have observed

New techniques for emulsion analysis in a hybrid experiment

23.2 \pm 6.0_{-0.9}^{+1.0}

Measurement of B (D(s)+ ---> mu+ muon-neutrino) / B (D(s)+ ---> phi mu+ muon-neutrino) and determination of the decay constant f(D(s))

purely-leptonic decays of

Measurement of the relative branching fraction Gamma (D0-->K micro nu )/ Gamma (D0--> microX).

D_s^+ ->\mu^+ \nu_\mu

Measurement of the lifetimes of charged and neutral beauty hadrons

from a sample of muonic one prong decay events detected in the emulsion target of Fermilab experiment E653. Using the

Erratum to:“Near muon range detector for the K2K experiment—construction and performance”: [Nucl. Instr. and Meth. 482 (2002) 244–253]

D_s^+ ->\phi \mu^+ \nu_\mu

Measurement of B(D s + ? +? ) B(D s + ? f +? ) and determination of the decay constant f D s

yield measured previously in this experiment, we obtain

Measurement of the relative branching fraction. Gamma. ( D sup 0 r arrow K. mu. nu. )/. Gamma. ( D sup 0 r arrow. mu. X )

B(D_s^+ -->\mu^+ \nu_\mu) / B(D_s^+ -->\phi \mu^+ \nu_\mu) =0.16 \pm 0.06 \pm 0.03